The present invention relates to a receptacle for a radioactive material container.
The use of medicinal grade radioactive solutions such as containing Tc.sup.99m is undergoing great expansion. A critical problem has arisen along with the increased use of these solutions. It is generally agreed that excessive exposure to even low level emission is highly undesirable as evidenced by the fact that there are federal regulations defining permissible exposure. In 10 CFR Part 20 there is defined the exposure level permissible. Accordingly, most generative and storage systems include protective shielding to bar the passage of emitted radiation. There are various devices now in use which provide adequate protection from radiation. It is, however, necessary that the fluid or material level be easily viewed so that it can be ascertained if there is sufficient fluid for the next application. In other words, it is highly undesirable for one to have to remove the container from its protective shielding merely to ascertain the fluid level thereof. This would result in unnecessary emission exposure which, according to the present invention, can be easily avoided.
The primary method of detecting the material level in a shielded container has been the provision of a viewing means, such as a window, made from such as leaded glass. There are a number of variations adapting this principle, such as those described in U.S. Pat. Nos. 3,286,095, 3,655,985, and 3,673,411. In U.S. Pat. No. 3,286,095 a box-like casing has a window comprising one side thereof, the interior of the casing always being in view. In U.S. Pat. No. 3,655,985 a lead casing includes a window which is filled with a transparent shielding material such as leaded glass. U.S. Pat. No. 3,673,411 incorporates an essentially similar window to that described in U.S. Pat. No. 3,655,985. All the foregoing patents have one common characteristic; at all times leaded glass or other transparent shielding material is exposed to the emissive contents and, more importantly, the viewer is always confronted by this shielding material. It is certainly accepted that a dense, non-transparent material such as lead has greater shielding characteristics than such as leaded glass. While the glass may provide sufficient shielding to maintain emissions under the mandated maximum, it is certainly worthwhile to reduce the exposure level under even that limit. Indeed, the optimum situation is to reduce exposure to zero, a level though not attainable, can be approached. The present invention is directed to reducing emission exposure as much as possible and well below the maximum permitted by law. In comparison to the devices thus described, it exhibits superior shielding characteristics and at the same time allows the material level to be simply ascertained.